Engineering Fusion with Tokamak

Could Tokamak Energy’s new CEO help the company crack grid-scale fusion power in under a decade? Molly Lempriere speaks to former engineer Jonathan Carling about the challenges and potential for success

TOKAMAK ENERGY WAS SET-UP IN 2009 BY RESEARCHERS FROM THE CULHAM FUSION RESEARCH GROUP, WITH THE GOAL TO CRACK NUCLEAR FUSION BY 2025 THROUGH PERFECTING THE SPHERICAL TOKAMAK. THE TOKAMAK USES HIGH TEMPERATURE SUPERCONDUCTORS TO CREATE THE POWERFUL MAGNETIC FIELD REQUIRED TO TRAP ELECTRICALLY CHARGED PLASMA PARTICLES, CONTAINING THE REACTION AND KEEPING IT HOT.

The superconductors consist of tapes as thin as 0.1mm made from rare earth barium copper oxide, wound into coils that provide a much higher magnetic field than their predecessors, while taking up less space. Tokamak reactors

have reached temperatures of hundreds of degrees, but challenges still lie ahead before economic fusion power can be achieved

and sustained.

In November 2017, Jonathan Carling was appointed as CEO of Tokamak Energy. The former Rolls Royce senior executive aims to help the company transition from physics proofs to a commercial energy source. So what are the challenges that lay ahead?

Jonathan Carling

CEO of Tokamak Energy

Molly Lempriere:

What do you think your engineering background will bring to Tokamak Energy?

Jonathan Carling:

What do you think your engineering background will bring to Tokamak Energy?

Jonathan Carling:

Tokamak Energy has reached a stage now where it's got a very good scientific base for its work.

A lot of the key challenges are around the engineering of the solutions and developing the operational framework for fusion energy. I've done a lot of that in my career, taking a new technology and engineering it into something which could actually be used by society and operated on a commercial basis.

That's the stage the company is at and I think it's an exciting stage. We are starting to run our ST40 reactor which [will] get up to 15 million degrees in the new year, as well as a big development programme next year. It will be great to work with the team on building that out, as we prepare for developing commercial fusion energy before 2030.

Can you elaborate on the predominantly engineering challenges you mentioned?

Can you elaborate on the predominantly engineering challenges you mentioned?

One good example would be the Tokamak Energy solution for fusion energy [which] is a spherical tokamak that uses high-temperature superconducting magnets; this will allow us to use much higher magnetic flux in the reactor to make a much more compact fusion reactor.

Now, the high temperature superconductors were only invented in the mid-80s and it's only really in the last ten years that these high-temperature superconducting tapes have become available on the market. The cost is starting to fall but there's still a lot of engineering development work to be done to create practical, large-scale, high-field magnets from these tapes.

It’s an area where we're very active: we've got over 20 patents in this space and we have a big development programme in our magnet laboratory for making those into commercially viable magnets.

So just within that one area of our programme, we have to engineer magnets that work, we have to mature the supply chain for the high-temperature superconductor itself. We have to bring all of that together into a solution which we can apply to the reactor.

There are lots of other similar challenges, where the technology exists and it's reaching commercial availability, but it's still got to be engineered into a final product and the supply chain and operational wherewithal still needs to be developed. When businesses fail to succeed with technical endeavours, it's often not at the invention stage, it's at the deployment stage.

How achievable are your five different steps to nuclear fusion proving?

How achievable are your five different steps to nuclear fusion proving?

It's going well. We've got major milestones around magnet development, the next milestone is a three tesla high-temperature superconducting magnet, and that's built and just being instrumented and uploaded into its cryostat.

So we expect that to happen certainly within the next few weeks.

On the tokamak itself, the last reactor that we built, the ST25, was the first reactor in the world to actually demonstrate a tokamak running with high-temperature superconducting magnets. The ST40 is a bigger machine and the goal for this is to demonstrate very high temperatures in a spherical tokamak, so early in 2018 we'll be developing 15 million degrees. At the end of next year we aim to be hitting our next milestone which is 100 million degrees.

Following on from that, we'll be looking to take the ST40 up to near-fusion conditions of around 150 million degrees. Then we'll be going onto our ST200 machine where we'll be demonstrating positive fusion energy and commercially available fusion energy by 2025, with an aim for electricity powering into the grid commercially by 2030. So it's a step-by-step process, with each step we have technical milestones that we need to hit. We need to hit them to prove our programme but also to prove to our investors that we're on track.

Image courtesy of Tokamak Energy

How does Tokamak Energy differ from other projects and companies pursuing nuclear fusion?

How does Tokamak Energy differ from other projects and companies pursuing nuclear fusion?

One other aspect of Tokamak Energy's approach that I find very interesting is this question of agility. Because we're using these very high field magnets, then our fusion reactors tend to be a lot smaller than some others because they're using very, very high magnetic fields.

Because they're much smaller and because we're privately funded, that makes us very agile. If we were making larger machines, or if we were going down a different funding route where we were dependant on grants and so forth, we wouldn't be able to make as many prototypes as we do at the rate we do, and we wouldn't be able to make decisions as quickly as we do.

It's an interesting dimension for me, there's the technical and operational aspect of how we get there, but I'm also very interested in our business because of our agility. That's something we're going to be relying on as we go forwards.

Could this benefit remote communities, as well as providing grid power?

Could this benefit remote communities, as well as providing grid power?

It's definitely very compatible with a modular concept, so you could have a power plant which actually has more than one reactor, and the number of reactors could be scaled according to the amount of power required. That suggests all sorts of interesting possibilities like having a more distributed grid with lower transmission costs. It does also offer the possibility of deployment in more remote parts of the world than ones with very high capital costs.

The tokamak seems to have many of the same positives as SMRs, but with the added benefit of fusion as opposed to fission. Is this correct?

The tokamak seems to have many of the same positives as SMRs, but with the added benefit of fusion as opposed to fission. Is this correct?

Yes, and because fission is an older technology there are probably SMR concepts that might be ready to go even sooner than a fusion SMR. But there are still fission reactors with high-level waste, the theoretical potential for meltdown risk that has to be managed away, and so on. It's still a fission reactor. So in the long-term, we may find that fission SMRs could be an interim solution, they may useful until fusion SMRs come onto the market. It will be very interesting to see how all of this develops.